Huiqiu Yuan
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Transcript of Huiqiu Yuan
Huiqiu YuanDepartment of Physics, Zhejiang University, CHINA
Field-induced Fermi surface reconstruction near the magnetic quantum critical point in CeRhIn5
Workshop on Heavy Fermion Physics: Perspective and Outlook, IOP, CAS, 2012/1/7-9
Collaborators
Zhejiang U: Lin Jiao Tian ShangYe Chen Jinglei Zhang LANL: Yoshimitsu Kohama Marcelo JaimeJohn Singleton Eric Bauer H. O. Lee Joe Thompson
MPI-CPfS: Frank SteglichRamzy Daou
Sungkyunkwa U:Tuson Park
Rice U: Qimiao Si
OUTLINE
Introduction The H-T phase diagram of CeRhIn5 Field induced changes of Fermi surface Summary and outlook
The global phase diagram in Kondo Lattice
H=Hf+Hc+Hk
= + + G=Innn/Inn: spin frustration
AFs: AFM with small FS, No static Kondo screening
PML: HF Fermi liquidKondo screening fully developed
AFL: Intermediate region. Kondo screening develops inside AFM state
Lifshitz transition
QM Si, Phys. B (2006)
I: Local QCPII: SDW-type QCP
YbRh2Si2: Prototype of local QCPYbRh2Si2: • T*: crossover temperature
for the Kondo breakdown.• T* meets TN line the QCP.
• Changes from small FS to large FS crossing the T* line?
• TFL: FL region.
CoRhIr: • Negative pressure,
suppressing AFM.• T* line reaches zero in AFM,
at QCP and away from QCP.• T* is determined by Hall
effect and thermal properties.
Problem: • Impossible to study the real reconstruction of FS.
S. Friedemann et al, Nature Phys. (2011)
-0.2 0.0 0.2 0.4 0.6 0.8 1.00.0
0.5
1.0
1.5
2.0
2.5
heavyfermion
CeCu6-xAux
T (
K)
x
AFmagnetic order
QCP
(H. von Lohneysen,‘96)
CeCu6-xAux: local vs. SDW QCP for doping vs. field-induced QCP?
E/T scaling of the inelastic neutron-scattering cross-section S in CeCu5.9Au0.1 : =0.75.
CeCu5.8Au0.2: field induced QCP at B~0.35T! HMM scenario fits better!
A. Schröder, Nature (2000)
O. Stockert,
PRL(2007)
Quantum criticality: various tuning parametersN. Harrison et al, PRL (2007)
Pressure: Small FS to large FS at Pc=2.6 GPa Delocalization of f-electrons?
Magnetic field: Polarization of f-electron moments Small FS above Hc=61T.
Issues:
• Quantum criticality tuned by various parameters (e.g., H, P …) Similar or different?
• Direct evidence of Fermi surface reconstruction around the QCP?
Heavy fermions CeMIn5 (M = Co, Rh, Ir)
Co3d7 4s2
Ni3d8 4s2
Fe3d6 4s2
Rh4d8 5s1
Ir5d7 6s2
Pd4d10 5s0
Ru4d7 5s1
Pt5d10 6s0
Os5d6 6s2
Cu3d10 4s1
Mn3d5 4s2
1) CeCoIn5 (M=Co) – heavy fermion SC C/T = 290 mJ mol-1 K-2 at Tc = 2.3 K
2) CeIrIn5 (M=Ir) – heavy fermion SC C/T = 700 mJ mol-1 K-2 at Tc = 0.4 K
3) CeRhIn5 (M=Rh) – AFM C/T = 420 mJ mol-1 K-2 at TN = 3.7 K, Q = (1/2, 1/2, 0.297), meff = 0.79 mB (0.84)
M=Co, Rh, Ir
In(2) site
In(1) site
Petrovic et al. JPCM 13, (2001)
M-In
Ce-In
Ce-In
CeRhIn5: Localized 4f-electrons?
N. Harrison et al, PRL (2004); H. Shishido et al, JPSJ (2002); D. Hall et al., PRB (2001);S. Elgazzar., PRB (2004)
Comparison of exp. and theory.Calculations assuming localized f-el.
Similarity between LaRhIn5 and CeRhIn5
T. Park et al, Nature (2006)G. Knebel et al (2006)
G. Knebel et al (2006)
CeRhIn5: pressure induced QCP
• Magnetic order disappears around 1.9 Gpa where TN=Tc.
• Pressure induced QCP at pc=2.4GPa.
• Field induced magnetism inside the superconducting state.
Dramatic changes of Fermi surface at p-induced QCP
• Dramatic changes of dHvA frequencies at Pc =2.4GPa.
• Sharp enhancement of m* at Pc.
• Evidence for local AFM QC or valence QC?
• Complications of magnetic field effect on the AFM transition!
H.Shishido et al, JPSJ (2005)
CeRhIn5: Any new physics in high field?
T=0K
T. Takeuchi et al., JPSJ (2001)S. Raymond ey al, JPCM (2007)
The magnetic order and its field dependence in CeRhIn5
k=(1/2, 1/2, 1/4)
(1/2, 1/2, 0.298)
(1/2, 1/2, 0.298)
• HM~2.5T: metamagnetic transition from incommensurate AFM to commensurate one.
• AFM seems to be suppressed by applying a magnetic field of 50T.
Experimental setup for ac specific heat measurements in a pulsed
magnetic field
Yoshimitsu Kohama et al, Rev. Sci. Ins. (2010)
Thank you!
P. Gegenwart et al, Nature Physics (2008)
Magnetic quantum criticality: Two scenariosSDW QCP
Local QCP
• Parameter can be tuned by doping, pressure and magnetic field.• E*loc characterizes the breakdown of the entangled Kondo singlet state.• Critical modes: fluctuations of magnetic order parameter (SDW type); additional modes related to the breakdown of Kondo effect (local QCP).• f electrons: itinerant (large Fermi surface) or localized (small Fermi surface)?
CeCu2Si2, CeNi2Ge2…YbRh2Si2, CeCu1-xAux
Local QCP
P. Gegenwart et al, Nature Physics (2008)
dHvA effect and Fermi surface topology Landau quantization: Quantization of orbital motion of a charged particle in a magnetic field.
Allowed orbits are confined in a series of Landau tubes, constant energy surfaces in k-space. Magnetization, resistivity etc: periodic function of 1/B.
dHvA effect:
Fi: oscillatory “dHvA” frequency;Si: Fermi surface extremal cross-section in plane perpendicular to B.
Fermi surface topology:
Conditions for the dHvA effect: Large magnetic field and low temperature For m* = 100 me: B/T >> 75 T/K HF: very high fields are required
High quality samples
Measurements of dHvA effect in a pulsed magnetic field
Induced voltage :V=d/dt (: magnetic flux, surface integral of B through the coil)B=m0(H+M)
V dM/dt=(dM/dH)(dH/dt) (V=0 for empty compensated coil)
Magnetic susceptibilityc V/(dH/dt)dH/dt measured by an additional coil surrounding the signal coil.
Coil compensation:When the probe is used, the induced voltages from both the signal coil and the compensation coil are amplified. A fraction of the voltage from the compensation coil is then added to or subtracted from the signal coil voltage to null out any remaining induced voltage.
H
sample
signal coilcompensation coil